1. Field of the Invention
The present invention relates to a safety syringe, especially to a safety syringe that can retract the used needle easily.
2. Description of the Prior Arts
U.S. Pat. No. 5,575,774 disclosed a safety syringe with retractable needle to reduce injuries to health care workers.
The safety syringe in accordance with the prior art has a barrel, a needle holder and a plunger. The barrel has an inner surface and an inside flange. The inside flange is formed on the inner surface and has a diameter. The needle holder has a holding space and a retaining hole. The holding space corresponds to the inside flange and has a diameter. The diameter of the holding space is larger than the diameter of the inside flange. The plunger has a retainer rod formed on a proximal end of the plunger. The retainer rod corresponds to the retaining hole. During use, the retainer rod is pressed into the retaining hole of the needle holder so the retainer rod engages the needle holder. After use, the plunger may be extended, pulling the needle into the barrel for improved safety.
However, the holding space of the needle holder and the inside flange of the barrel must be manufactured accurately to ensure correct fitting and combined with correct tightness to ensure correct functioning. Otherwise, the needle can fall off the needle holder or can not be pulled into the barrel so that the health care workers injured.
To overcome the shortcomings, the present invention provides a safety syringe to mitigate or obviate the aforementioned problems.